1. Field of the Invention
This invention relates to a battery device having a large number of secondary batteries. More particularly, it relates to a battery device for loading on a mobile system, such as a, electric vehicle, in which the battery device or an internal combustion engine are selectively switched for use as a driving source.
2. Description of the Related Art
In an automotive vehicle, attention is directed to practical use of an electric vehicle, having a battery device as a driving source, as a substitution vehicle for the gasoline engine vehicle or a diesel engine vehicle, in order to accommodate the problem of resources and environment. For an automotive vehicle, lead accumulators have so far been used as the electric driving source. Thus, in the electric vehicle, development of the driving source has been centered about this lead accumulator. However, a problem is raised in that the accumulator tends to be increased in size and weight in order to realize a practical running distance by charging only once.
Thus, in an automotive vehicle, attempts are conducted towards developing a so-called hybrid car in which a motor and a conventional engine are suitably switched, depending on the running conditions of the vehicle, to suppress the battery device supplying the power to the motor from increasing in size and to realize energy saving and cleanness. On the other hand, a battery device for an automotive vehicle is required to satisfy the specifications for high voltage of tens to hundreds of volts, a high energy density or a high output, so that attempts are being made to adopt a high-performance lithium ion secondary battery in place of the conventional lead cell. For example, in Japanese Laying-Open Patent H-9-86188 entitled xe2x80x9cBattery Structure for Electric Vehiclesxe2x80x9d, there is disclosed a battery device for an automotive vehicle having a large number of lithium ion secondary batteries housed in a battery casing.
Meanwhile, if, in a battery device for an automotive vehicle, the above-described specifications are to be satisfied, the voltage state of the large number of the lithium ion secondary batteries needs to be monitored and controlled to a constant state. To this end, a cell control unit having the functions of voltage detection or control or the input/output function for detection or control signals is annexed to the battery device for the automotive vehicle to improve the safety and reliability. The cell control unit carries thereon a micro-processor or electronic parts, and is connected to sensing lines connected in turn to respective lithium ion secondary batteries.
In the battery device for an automotive vehicle, the voltage value of each lithium ion secondary battery, obtained via e.g., a sensing line, is compared to a reference voltage value, and corresponding detection data are sent to the control device. The battery device for the automotive vehicle is controlled to a constant state by charging or discharging of the lithium ion secondary batteries under a control output from the control device.
In the battery device for an automotive vehicle, a large number of the lithium ion secondary batteries are housed within the battery casing, as described above. These lithium ion secondary batteries are monitored and controlled by a cell control unit. Meanwhile, in the conventional battery device for an automotive vehicle, the battery casing and the cell control unit are constructed independently of each other. Thus, in conducting a performance test, for example, it is necessary to interconnect a terminal of the battery casing to the cell control unit, to interconnect the device to a tester and to dismount the connection after the test, by a laborious operation.
On the other hand, in the battery device for the automotive vehicle, since a loading unit for the battery casing and a loading unit for the cell control unit are constructed on the vehicle independently of each other and connected to each other by electric wiring, the loading units are complicated in structure. If the loading units are spaced away from each other, means must be provided for elongated wiring extension and protection for wiring.
On the other hand, it is necessary in the battery device for an automotive vehicle to protect the device against occurrence of inadvertent accidents and to continue the monitoring and control of the lithium ion secondary battery. However, in the battery device for the automotive vehicle, since the battery casing and the cell control unit are constructed independently of each other, it is a frequent occurrence that the operation becomes impossible due to e.g., wiring breakage.
Moreover, in the battery device for an automotive vehicle, which is loaded below a flooring of the automotive vehicle, it is necessary to assure sufficient reliability against the heat radiated from the road surface, flooding in water during running in rainy weather or abrupt changes in temperature. In the battery device for an automotive vehicle, not only the battery casing or the cell control unit but also the wiring needs to be constructed to meet the above requirements, thus complicating the overall structure. In addition, in the battery device for the automotive vehicle, sufficient reliability needs to be maintained against large vibrations occurring during vehicle running.
It is therefore an object of the present invention to provide a battery device for loading on a moving system in which a cell control unit having the function of detecting or controlling the voltage of the secondary battery or the input/output function of the detection or control signals is built in a modular casing, housing therein a large number of secondary batteries, to assure facilitated handling and improved reliability.
The present invention provides a battery device for a mobile body including a modular casing of synthetic resin, defining a battery casing having a large number of terminal openings opening on both lateral sides, a large number of chargeable secondary batteries loaded in the battery casing, a plurality of cell control units and an exterior casing split into at least two casing halves and which delimits a housing spacing for the modular casing in its inside in the assembled state of the casing halves.
Each set of secondary batteries is loaded in the battery casing of the modular casing so that the positive electrode terminals and the negative electrode terminals are alternately exposed in neighboring terminal openings and so that the secondary batteries are connected in series to one another. A pre-set number of secondary batteries are grouped together as a set, with the totality of the secondary batteries being arranged in a plurality of such sets. The cell control unit includes a micro-processor, circuit elements or electronic components loaded on a circuit board and has the function of detecting and controlling the voltage of each battery module and each secondary battery. The exterior casing is provided with a positive electrode terminal, a negative electrode terminal and a transmission/reception terminal of the cell control unit.
In the above-described battery device for the mobile body according to the present invention, the secondary batteries are loaded in the battery casing of the modular casing and connected in series with one another and to a sensing line. In the battery device for the mobile body, each sensing line is connected to an associated cell control unit and subsequently each cell control unit is assembled to the modular casing. The modular casing is accommodated in the housing spacing of the exterior casing, the secondary battery sets, the positive electrode terminal and the negative electrode terminal are interconnected and the cell control unit is connected to the input/output terminal.
Since the battery device for the mobile body is constructed as what may be termed an all-in-one unit, it is directly loaded on a battery loading unit of the mobile body and connected to a controller of the mobile body via the positive electrode terminal, negative electrode terminal and the input/output terminal. Since the battery device for the mobile body is handled as a one-unit device in performance tests or maintenance, it can be handled easily, whilst its wiring can be simplified in structure. The battery device for the mobile body has the state of the secondary batteries and that of the battery sets monitored and controlled by the cell control unit and hence it can furnish the power in stability to improve the operational reliability.
With the battery device for the mobile body, according to the present invention, a large number of secondary batteries, a modular casing having a large number of battery housing sections each loaded with a secondary battery and a plurality of cell control units, each having the function of detecting and controlling the voltage of the sets of the secondary batteries and the function of inputting and outputting detection and control signals, are housed in an exterior casing to constitute as it were an all-in-one unit. Thus, it suffices to mount the unit on a battery loading unit of the mobile body and to connect the unit via the positive electrode terminal and the negative electrode terminal provided on the exterior casing to the mobile body. In performing performance check, the unit can be connected by itself to a testing device or dismounted from it for maintenance or other operations. Since the monitoring and control of the states of the respective secondary batteries can be performed reliably by the cell control units, the battery device for the mobile body is high in safety and reliability and can be handled extremely easily.